Police are investigating claims that El-Hadji-Diouf spat at an 11-year-old Middlesbrough fan during Bolton's 1-1 draw at the Riverside on November 7.

The incident is alleged to have happened when Diouf was substituted in the closing minutes of the game. The striker was booed by home supporters as he walked off the pitch and took a mouthful of drink and spat it in the direction of the stands.

The young Boro fan James Shield said: "I was sat behind the Bolton subs who were in the dug-out. Diouf just turned round and spat between the glass of the dug-out. It was orange juice or Lucozade. It just flew through the gap and hit me."

The Senegal international has been a controversial figure since Liverpool paid £11m for him after the 2002 World Cup.

He was fined £5,000 at Glasgow Sheriff Court when he pleaded guilty to assault under provocation for spitting at Celtic fans during Liverpool's Uefa Cup quarter-final at Parkhead in 2003, and in November 2002 he was accused of spitting at West Ham fans.